For now, parts of Montana, Wyoming, Colorado and the Dakotas were bearing the worst of it, with temperatures as low as minus 14 overnight

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The first arctic blast of the season has hit mainland United States, blanketing parts of Montana, Wyoming, Colorado and the Dakotas with temperatures as low as minus 14 overnight, NBC News reported.

But meteorologists are warning about a second, perhaps even colder freeze that could spread into the East Coast and possibly portions of the South late next week. A shift in a weather system known as the Polar Vortex may be partially to blame, according to The Weather Channel.

By Friday evening these frigid temperatures were expected to have swept most of the U.S. with temperatures in the 20s from Albuquerque to Buffalo, and from Atlanta to Seattle. New York, Washington, D.C., and Boston were also expected to flirt with freezing temperatures Friday night.

"It's going to be a shock," said Kevin Roth, senior meteorologist at The Weather Channel.